Here is a very simple PreAmp. Which anyone can build. You can use any N-channel JFET, even a MOSFET if you’re looking to experiment. It has a small footprint, so you can put it into just about any small enclosure. Also works very well with Piezos & will actually boost its volume as well as improve its tone? Has everything but a footswitch, which can easily be added if you’re going between two pickups.
Very cool Brian!